So, I managed to recover my search engines.
Had to delete two directories :
qBittorrent/nova3/__pycache__/
qBittorrent/nova3/engines/
And this file:
qBittorrent/nova3/__init__.py
Works fine now, after reinstalling the scripts. It was a reported bug in 2019 (!!!) and it obviously hasn’t been fixed.
I’ll look into jackett though, it looks like it replaces Prowlarr now.
M.